This invention relates to tire pressure gauges and more particularly to gauges that are permanently or semi-permanently mounted on a vehicle wheel.
Recent well-publicized events involving catastrophic failure of vehicle tires, often resulting in death and grievous bodily harm, have reemphasized the importance of maintaining proper inflation pressure on all tires at all times. Where proper tire inflation pressure is not maintained, tires will wear prematurely, exhibit degraded handling characteristics and, where they""re already worn or defective, potentially suffer complete failure.
While the majority of vehicle operators and motorists are aware of the importance of a maintaining proper inflation pressure, the near-elimination of full-service stations, and reduction in number of user-serviceable components on automobiles, has reduced the likelihood that full attention will be paid to tires and rims. In addition, a proper check of tire pressure typically involves the application of a discrete tire pressure gauge to the valve stem of each wheel, after unscrewing the step cap. Many vehicle operators do not even carry such a gauge, or if they do, it is often misplaced or inaccessible when needed (e.g. buried in the trunk or between seat cushions). Furthermore, it is less likely that the average motorist will take the time to perform this necessary or complex task in today""s overscheduled world. Consequently, a check of tire pressure will occur, if at all, only when a tire appears visually low on pressure. At this point, the tire is, in fact, dangerously low.
Some military and commercial vehicles assist operators in determining pressure by providing fixed gauges with respect to each wheel. These gauges are mounted firmly on the wheel or axle, and generally are part of the vehicles original equipment. In any case, these specialized wheels are purpose-built to receive the gauge. In fact, some military vehicles completely alleviate the problem of low tire pressure by providing integral tire inflation systems, typically using the axles as pressure conduits. These systems are prohibitively expensive and complex for all but the most high-end sport utility vehiclesxe2x80x94the civilian Hummer(copyright) manufactured by American General for example.
While there have been proposals in the prior art to provide basic tire pressure gauges to portions of wheels on more-common passenger cars, these have generally involved rather unaestethic or complex mounting arrangements that may include the drilling and tapping of air feed/mounting holes into the pressurized rim.
Accordingly, it is an object of this invention to provide an easily readable and mountable pressure gauge for application to a wheel of a vehicle. The gauge should be unobtrusive or otherwise aestethically intergrated into the design of the wheel. The gauge should not require any significant alteration to the underlying wheel structure or tire and should be easily mounted by either a home user or moderately equipped tire shop. It should be mountable on a variety of wheel types including those with one-piece alloy construction and those using separate hubcaps or beauty rings. The gauge should also be capable or integrating modern electronics for further versatility.
This invention overcomes the disadvantages of the prior art by providing a tire pressure gauge for mounting on a vehicle wheel, and associated interconnections, that enable the gauge to placed in direct pressure/fluid communication with a preexisting pressure inlet/outlet of the wheel such as a valve stem.
According to one embodiment, the tire pressure gauge is mounted on either an edge of the rim, in a location that is discreet-but-visible, or on a center/hub area of the wheel. The mounting can be either with respect to a solid alloy-style rim or a hubcap that is removable. A variety of mounting techniques can be employed including water-resistant adhesive (such as silicone), double-sided exterior grade tape, rivets or screws. The gauge can be mounted directly to the underlying rim portion or, it can be carried on a mounting plate that is flush against the rim, or raised up. Particularly where the gauge/display is electronic, it can be integrated into the appearance of the wheel. One specific location for a light-up electronic display is in a darkened area on the center hub area. Such an electronic gauge can be actuated by pressing or otherwise switching on the wheel hub area.
Pressure can be channeled to the gauge, regardless of location, through an appropriately sized tube capable of withstanding normal tire pressures without breaking, splitting or disconnecting. The tube can be interconnected with a separate saddle valve that is applied over, and forms a seal with respect to, the tire""s existing valve stem. A secondary fill outlet with cap and press valve can be provided on the saddle valve. The saddle valve can include a centered nub for pressing down the preexisting press valve on the valve stem when it is attached and fully secured. In this manner, pressure is communicated from the original stem to the saddle valve, and whence to the pressure gauge feed tube. Alternatively, the valve stem of the wheel can be replaced with a modified valve stem having a tap that directs pressure to the gauge feed tube, the tap being positioned below the level of the press valve so that constant fluid communication is maintained.
According to the invention, the saddle valve, or another portion of the valve stem can be spring-loaded so that it directs pressure into the gauge only when the spring-loaded feature is actuated by an applied force. In this manner, the press valve seal of the original valve stem can be maintained, and the possibility of leakage through the saddle valve or tap is minimized. A locking mechanism may be employed to continuously actuate the spring-loaded feature, even in the absence of an externally applied force. That is, an external force may initially actuate the spring to establish constant fluid communication between the valve stem and the pressure gauge. Thereafter, the locking mechanism can maintain the constant pressure flow to the gauge once the external force is removed. The saddle valve can be provided with a separate, typically top-mounted, filler tap and press valve.
In an exemplary embodiment, the spring-loaded saddle valve is depressed by an applied force, thereby driving its centered nub downward onto the preexisting press valve in the tire""s valve stem. The centered nub, in turn, bears downwardly against the preexisting press valve, enabling air to flow from the tire into the saddle valve to a pressure gauge coupled to the saddle valve. The saddle valve may be secured in this position by engaging a locking mechanism on the saddle valve, thereby providing constant air flow from the tire to the gauge, even in the absence of the applied force. When the saddle valve is no longer depressed by the applied force or the locking mechanism, the restoring force of the compressed spring lifts the centered nub from the tire""s press valve, consequently shutting off air flow from the tire.
An air hose may be applied to the filler tap of the saddle valve to direct air flow from the hose to the tire. In the exemplary embodiment, a downward pressure may be applied to the spring-loaded saddle valve to enable air communication between the tire and the saddle valve, and application of the hose may depress the filler tap""s press valve enabling air communication between the saddle valve and the hose. A locking mechanism on the saddle valve may be engaged to maintain air flow from the saddle valve to the tire even when the downward pressure is removed. This locking mechanism can be actuated by rotating an upper member of the saddle valve with respect to a base member that is attached to the tire stem. In an alternate embodiment, when the air hose is applied to the filler tap, it depresses the saddle valve""s press valve while the pressure moves the saddle valve downwardly to depress the original valve stem press valve, thus completing a connection that enables air to flow into the wheel.
Finally, according to another alternate embodiment, each saddle valve can comprise a compact pressure transducer, of the type used generally in commercially available electronic tire pressure gauges. The transducer can drive a digital display located on the saddle valve. Alternatively, the transducer can transmit telemetry to a compact electronic radio transmitter that transmits an encoded radio signal at a desired interval to a main receiver in the vehicle passenger compartment so as to continuously update the receiver with tire pressure information for each of the vehicle wheels being monitored.